Electrical timepiece



Nov. 22, 1960 M. HETZEL 2,960,817

suscmxcm. TIMEPIECE Filed May 14, 1956 7 Sheets-Sheet 1 INVENTOR- M anHejze.

Nov- 22, 19 Q M. HETZEL 2,960,817

ELECTRICAL TIMEPIECE Filed May 14. 1956 7 Sheets-Sheet 2 I a F/G'. 3

IN V EN TOR.

Nov. 22, 1960 M. HETZEL 2,960,817

ELECTRICAL TIMEPIECE Filed Ila} 14, 1956 7 Sheets-611a 3 4% FIG.

2a: 2; 43 304 FIG. /3

503 4 305 INVENTOR: M M Hum Nov. 22, 1960 M. HETZEL ELECTRICAL TIMEPIECE7 Sheets-Sheet 4 Filed lay 14, 1956 Nov. 22, 1960 M. HETZEL ELECTRICALTIMEPIECE '7 Sheets-Sheet 5 Filed May 14, 1956 INVENTOR: M (kX He'd-2 clmum 3 s vm /Q gt Nov. 22, 1960 M. HETZEL ELECTRICAL TIMEZPIECE 7Sheets-Sheet 6 Filed May 14, 1956 F/G. INVENTOR.'

M LK H+2\ (KQMQ shim Nov. 22, 1960 M. HETZEL ELECTRICAL TIMEPIECE '7Sheets-Sheet 7 Filed May 14, 1956 United States Patent cc ELECTRICALTIMEPIECE Max Hetzel, New Hyde Park, N.Y., assi nor to Bulova' WatchCompany, Inc., Jackson Heights, N.Y.

Filed May 14, 1956, Ser. No. 584,709 Claims priority, applicationSwitzerland May 12, 1955 3 Claims. cuss-23) The present inventionrelates to an electrical timepiece.

More particularly, the present invention relates to an electricaltimepiece incorporating a motion transformer capable of transforming theoscillations of a vibrator into rotary movement, which vibrator isoscillated by suitable means which are operatively associated therewith,the electrical timepiece being of the type disclosed in copendingapplications Serial No. 436,949 filed June 15, 1954, Serial No. 547,510filed November 17, 1955 (said application Serial No. 547,510 being aco'ntinu'ation of application Serial No. 463,462 filed October" 20,1954, now abandoned), Serial No; 565,451 filedFebruary 14, 1956, nowPatent No. 2,888,582, May 26, 1959 Serial No, 565,452 filed February 14,1956, Serial No. 570,958 filed March 12, 1956, and Serial No. 580,813,fi-l'ed' April 26, 1956 and entitled Motion Transformer, now Patent No.2,908,174; October 13, 1959. This application is acon tinuation-in-p'artof said copending application Serial No; 580,813.

It is an object of the present invention to provide an electrictimepiece which incorporates a motion transformer adapted to transformtheoscillations'of a vibrator into the rotary movement of the hands ofthe timepiece.

It is another object of the present invention to provide an electrictimepiece wherein the action of the vibrator is controlled in such amanner as to insurethe' accuracy of the timepiece.

It is a still further object of the present invention to provide anelectric timepiece wherein the amplitude of oscillation of the vibratoris controlled in such a manner as to insure the accuracy of thetimepiece.

The objects of the present'invention also include the provision of anelectric timepiece wherein suitable means are provided for oscillatingthe vibrator which serves to cause rotary movement of the hands of thetimepiece.

It isan additional object of the present inventionto provide an electrictimepiece the operation of which requires an extremely small amount ofpower.

It is yet' another object of the present invention to providean electrictimepiece wherein the means for oscillating thevibrator also control theamplitude of such oscillation.

It is still a further object of the present invention to provide-anelectric timepiece which is composed of simple and ruggedly constructedparts which may be massproduced at low cost.

The objects of the present invention further include the provision of anelectric timepiece which may be easily assembled and constructed andthus'be readily mass produced;

Also included among the objects'of thepresent invention is the provisionof an electric timepiece whichis extremely accurate and reliablein-operation and which will operate for very. long periods withoutrequiring winding oranyothe'r attention whatsoever.

With the above objects in view, the present'invention mainly consists inthat improvement in a -timepiece=having a timepiece mechanism whichincludes reciprocatable 2,968,81? Patented Nov. 22, 1960 2 driving meansfor driving the timepiece mechanism, a vibrator connected to the drivingmeans for reciprocating the same, and means for oscillating thevibrator.

More particularly, the present invention resides in that improvement insuch a timepiece wherein the driving means are operatively associatedwith the timepiece mechanism in such a manner that the timepiecemechanism is-drivenjby the driving means when the length of the strokeofreciprocation thereof is between a predetermined minimum stroke lengthand a predetermined maximum stroke length, wherein the vibratorreciprocates' the driving means with a stroke the length of which is afunction of the amplitude of oscillation of the vibrator, and whereinthe means for oscillating the vibrator are electrical means andoscillate the" vibrator at an amplitude at which the stroke length ofthe driving means is between the predetermined minimum and maximumstroke lengths.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims; theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereofl willbe best understood from the following description of specificembodiments when read in connection with the accompanyi'n'g drawings, inwhich:

Fig.- l is a plan view of the interior of a timepiece according to thepresent invention when seen from the rear Off the timepiece. Fig; 1showing diagrammatically how the electrical leads may be connected to astorage battery orthe'like when the timepiece is used, for example,as'an automobile clock, Fig. 1 further showing the timepiece asincorporating one preferred embodiment of a motion transformer mechanismcapable of transforming oscillations of a vibrator to rotary motion; 7

Fig. 2 is a'sectional elevational view taken along line ABCDEF of Fig. 1in the direction of the arrows;

Fig. 3 is a side elevational view of the structure of'Fig. 1 as seenfrom the left sideof the latter;

Fig. 4 is a fragmentary plan view similar to Fig. 1 showing" a variationaccording to which the structure of Fig. 1 may be connected'toa'diflerent source of electrical y;

Fig. 5 is a fragmentary perspective view of a part of a pawl ofthe'pres'ent invention as'seen in the direction of arrow G of Fig. 1;

Fig. 6' is a perspectiveview illustrating the connection of a pawl tothe tine of a tuning fork, the structure of Fig. 6 being shown in thedirection of arrow H of Fig. 1;

Fig. 7 is a wiring diagram of the electrical circuit of the timepieceshown in Figs. 1 to 6;

Fig. 8 is a diagrammatic view illustrating the interaction of a pawl andratchet wheel incorporated in a motion transformer of the typeillustrated in Fig. 1;

Fig. 9 is a diagrammatic showing of a modified embodiment of the presentinvention;

Fig. 10 is a diagrammatic view of another modified embodiment of thepresent invention;

Fig. 11 is a diagrammatic view of yet another modified embodiment of thepresent invention;

Fig. 12 is-a fragmentary diagrammatic view of a still further modifiedembodiment of the present invention;

Fig. 13 isa fragmentary diagrammatic view of yet another modifiedembodiment of the present invention;

Fig. 14 is a fragmentary diagrammatic view of a modified embodiment of amotion transformer mechanism incorporated in a timepiece of'the typeillustrated in Fig. 1;

Fig. 15 is a fragmentary diagrammatic view, on an enlarged scale, ofanother modified embodiment of a motion transformer mechanism;

Fig. 16 is a fragmentary diagrammatic view, on an en- 3 larged scale, ofyet another modified embodiment of a motion transformer mechanism;

Fig. 17 is a sectional view taken along line A-A of Fig. 16;

Fig. 18 is a fragmentary diagrammatic view, on an enlarged scale, of astill further modified embodiment of a motion transformer mechanism;

Fig. 19 is a fragmentary diagrammatic view, on an enlarged scale of astill further modified embodiment of a motion transformer mechanism;

Fig. 20 is a fragmentary perspective view, partly in section and on anenlarged scale, of a tuning-fork type vibrator, a pawl and ratchet typemotion transformer mechanism actuated by the vibrator, and electricalmeans for oscillating the vibrator;

Fig. 21 is a wiring diagram of the electrical circuit of the electricalmeans shown in Fig. 20; and

Fig. 22 is a graphical representation of certain voltages and currentsas a function of time.

' Referring now to the drawings, it will be seen that the timepieceincludes a base plate 1 which is made of a circular plate having asubstantially constant thickness. A vibrator 2 which is preferably of atuning fork type is fixed to a member as by soldering or welding or thelike, this member 5, in turn, is fixed to the base plate 1 by a pair ofscrews 5a. As is clearly shown in Figs. 1 and 3, the member 5 isconnected to the tuning fork 2 only at that part thereof whichinterconnects the tines 3 and 4, so that the latter are maintained inspaced relation to the base plate 1 and are free to oscillate.

. At the free end of the tine 3 there is located a permanent magnet 6 inthe form of a hollow cylinder which is open at one end and which has anend wall 6b closing the cylinder 60, this end wall 612 carrying amagnetic bar 6a which is of very strong magnetic material, as forexample, Alnico.

' The other tine 4 of the tuning fork 2 carries at its free end abalance weight 7 which may simply be in the form of a cylindrical blockfixed in the manner shown in Fig. 1 to the free end of the tine 4. Thetines 3 and 4 and the masses of the permanent magnet 6 and the balanceweight 7 are so chosen that the tine 3 and the permanent magnet 6 on theone hand and the tine 4 and the balance weight 7 on the other hand haveapproximately the same natural frequency so that the tuning fork willnot require an undesirable large amount of damping. Also, thearrangement of the parts is such that the centers of gravity G of thepermanent magnet6 and the balance weight 7 are in alignment with thetines 3 and 4, respectively. As a result, it is possible for the tines 3and 4 to oscillate at constant frequency while requiring an almostnegligible amount of energy, as set forth in copending applicationSerial No. 565,451.

The counter weight 7 carries an abutment element 7b which is preferablymade of non-magnetic material, as, for example, brass. The abutmentelement 7b extends toward the permanent magnet 6 and is spaced therefroma distance s.

As is well known, the tines of a vibrating tuning fork type vibratornormally oscillate toward and away from each other, i.e., inwardmovement of one tine from its normal rest position is accompanied by acorresponding inward movement of the other tine and outward movement ofone tine is accompanied by a corresponding outward movement of the othertine. Also, the inward deflection of each tine is equal to its outwarddeflection, so that the amplitude of oscillation of each time is equalto twice the deflection of each tine from its rest position to its innerdeflected position.

It will be seen, therefore, that the maximum amplitude of oscillation ofeach tine 3 and 4 is equal to the length of the distance s inasmuch asthe maximum possible inner deflection of each tine is equal to one-halfs.

The purpose of the abutment element 7b and the factors influencing theselection of the distance s will be discussed below.

Also, suitable abutments 3a and 4a are carried by the base plate 1 andserve to limit the outwardmost deflection of the tines 3 and 4,respectively. The distances between the abutment 3a and the time 3 andbetween the abutment 4a and the tine 4 are considerably greater than theabove described distance s, so that the tines will engage theseabutments only when the timepiece is exposed to excessive shocks. Thus,the abutments are normally not contacted by the tines but serve only toprotect the same from damage in the event the timepiece is subjected tovery large shocks.

If desired, the balance weight 7 may be provided with a threaded bore 7ain which a screw member 8 is threadedly located. The screw member 8 isshorter than the length of the threaded bore so that the screw membermay be shifted toward or away from the tine 4 along a line forming anextension of the latter. In this way, the center of gravity of thebalance weight 7 is shifted along this line simply by varying theposition of the screw 8. As a result, the natural frequency of the tine4 may be varied, the center of gravity of the balance weight 7, however,at all times remaining in registration with the tine 4. Inasmuch as thenatural frequency of the entire tuning fork 2 is the average of thenatural frequency of the two tines, it is possible to change the naturalfrequency of the entire tuning fork by shifting the screw 8. In thisway, it is possible to regulate the time which is kept by the timepiece.Thus, if there are relatively small variations between the naturalfrequencies of the tines and the weight and permanent magnet,respectively carried thereby, such small variations in the naturalfrequencies will not influence the operation of the timepiece. When thelatter is first manufactured, the relative natural frequencies of thetines and the parts carried thereby are so regulated, as, for example,by filing off a part of one tine, that the t mepiece keeps perfect timeto within plus or minus three minutes, for example. By shifting thescrew member 8 in the balance weight 7 it is possible to provide a veryfine adjustment which will enable the timepiece to keep accurate timewithin this range of plus or minus three minutes per month.

The above described adjusting or compensating arrangement is describedin copending application Serial No. 565,452.

In the chamber 9 within the drum magnet 6, there is located a tubularcarrier 10 which is fixed to a support 13, the latter in turn beingfixed to the base plate 1 by means of screw members 14, as is shown inFigs. 1 and 3. The tubular member 10 freely surrounds the core 6::without contacting the latter, and the tubular member 10 carries a pairof coils 11 and 12, the coil 12 having approximately five to six timesas many turns as the coil 11. The core 6a has suflicient clearancewithin the tube 10 to avoid contacting the latter during oscillations ofthe tines 3 and 4 of the tuning fork. Thus, the coils form with thepermanent magnet 6 a transducer which, together with the tuning fork 2,forms a tuning fork oscillator of the same general type as thatdisclosed in copending application Serial No. 436,949.

7 At the left face of the support 13, as viewed in Fig. 1, and as isshown in Fig. 3, there is fixed a resilient strap 33 which serves tomount on the support 13 a capacitor 34, a resistor 35, a transistor 19,and a capacitor 40. Furthermore, the support 13 carries a pair ofinsulated electrical terminals 15 and 16 which are electricallyconnected to the lines 22 and 23 which in turn are connected to a sourceof electrical energy. According to the embodiment of the invention shownin Fig. 1, the source of energy is the storage battery 17 of anautomobile. In general the voltage of such an automobile battery is toogreat for the purposes of operating a timepiece of the type disclosed,so that this battery is not connected directly to the timepiece. Thelines 22 and 23 are com 3 nec'tedin the manner shown in Fig. 1 to theresistor 18, and the end 18a of the line 23 forms with the resistor 18 avoltage divider, this voltage divider being located outside of thetimepiece, although it could of course be located within the casing ofthe timepiece and fixed to the base plate 1, if desired.

When the above described electronic circuit is connected to the sourceof energy, the electrical circuit is closed and the oscillations of thetuningfork are started and are maintained by the sourceof energy. Thetuning fork starts oscillating as soon as the circuit is closed becauseit is quite sensitive and picks up any vibrations which are present inthe surrounding atmosphere or in the base plate 1. With an arrangementas described above it is possible to obtain a frequency constant to twoparts in 10 while for a timepiece of thetype described above a frequencyconstant to one part in 10 is more than adequate. The oscillations ofthe tuning fork must be converted into a rotary movement in order to beuseful in the timepiece, and this conversion can take place by thetransmission means illustrated. in Figs. 1, 2, 5 and 6.

A pawl 20 is carried by the tine 4 of the tuning fork 2, this pawl 26being in the form of a relatively light leaf spring and being fixed tothe tine 4 by means of a pin 20, as shown in Fig. 6. The tine 4 isformed with a relatively shallow bore which does not extend more thanone quarter of the way through the tine 4 and into which bore the pin20' is pressed, so that in this way the natural frequency of the tine 4is influenced to but a very negligible extent. The leaf spring 2% isfixed to the pin 20', as by being soldered thereto, in the manner shownin Fig. 6, and at its free end leaf spring 20 carries the tooth member20a made of a very hard material such as glass or hardened steel. Also,precious or semiprecious stones such as rubies or sapphires areparticularly suitable for this purpose. As is evident from Fig. 5, themember 20a is wider than the leaf spring 20 and extends beyond thelatter, and this member 215a is fixed to the leaf spring 29 by asuitable adhesive material, for example. The member Zila is preferablyformed with a sharp edge.

This member 20a of the pawl cooperates with the teeth of the ratchetwheel 21 so that the oscillations of the tine 4 transmit turningimpulses to the ratchet wheel 21 through the pawl 20. In this way theratchet wheel 21 is turned through a predetermined angle at everyoscillation. As is evident from Fig. 2, the ratchet wheel 21 and thepinion 21a are fixed to a common shaft which extends through the baseplate 1. In addition, this common shaft extends through an opening of adished spring 33 which bears against part of the ratchet wheel 21 andurges the latter away from the base plate 1, so that dished spring 33acts as a brake retarding the turning movement of the ratchet wheel 21.The spring 33, the ratchet whee 21, as well as the pawl 29 and member20a are carefully designed and chosen so that at each oscillation theturning movement transferred to the ratchet wheel 21 by the leaf spring20 will result only in a turning of the ratchet wheel in the desireddirection through a distance of one tooth. In other words thearrangement is such that the ratchet wheel 21 cannot overrun or turnfreely beyond the distance through which it is turned by the pawl.Furthermore the frictional resistance provided by the spring 33 is suchthat during the return movement of the pawl 20 the ratchet wheel 21 alsodoes not turn and the tooth member 2&2 runs over a tooth of the ratchetwheel, to engage in the next space between the teeth. In this way aturning movement is imparted to the ratchet wheel 21 which compels thelatter to rotate at a rate, i.e., at a number of revolutions per unittime, which has a direct relation to the rate of oscillation of thetuning fork 2r.

Inasmuch as the tuning fork oscillates at a constant rate, the ratchetwheel 21 also turns at a constant speed and in one direction. A geartrain is provided to trans mit the turning of the ratchet wheel 21 tothe hands of the clock, and this gear train includes the pinion 21a, the

gear 22 meshing with the pinion 21a and turning together with the pinion22a which meshes with the gear 23 which turns together with the pinion23a. The pinion 23a meshes with the gear 24 which turns the pinion 24a,the latter meshing with the gear 25 which turns together with the pinion25a. The gear 25 is fixed as by a press fit to the shaft 251) to whichthe pinion 25a also is fixed, and this shaft 25b extends all the way upto the unillustrated' face of the clock which carries the numbers.

The frequency of oscillations of the tuning fork and the number of teethof the ratchet wheel 21 as well as the different transmissionratiosbetween the several driving and driven gears are so chosen thatthe shaft 25b makes one complete revolution in an hour. Thus, the minutehand is fixed to the shaft 25b.

The speed of the minute gear 25 is reduced to one twelfth in a knownway. Thus, the gear 25a meshes with a gear 26 which turns together withthe pinion 26a, the latter in turn meshing with a gear 27 aflixed to thesleeve 28 freely turnable on the shaft 25b. These gears 25a, 26, 26a,and 27 give to the sleeve 28 a speed of rotation which. is one twelfththat of the shaft 25b, so that the sleeve 28 turns through a completerevolution in twelve hours, and thus the hour hand is fixed to thesleeve 28.

If, for example, the tuning fork oscillates at cycles per second, thenthe various pinions and gears can have the following numbers of teeth toprovide the desired transmission to enable accurate time to be kept fromthe tuning fork.

Pinion or gear: Number of teeth Ratchet wheel 21 360 Pinion 21a 6 Gear22 30 Pinion 22a 6 Gear 23 a- 36 Pinion 23a 6 Gear 24 42 Pinion 24a 6Minute wheel 25 50 Pinion 25a 10 Gear 26 30 Pinion 26a 8 Hour wheel 2732 A consideration of the above numbers of teeth will show that theminute wheel makes one revolution an hour and the hour wheel makes onerevolution in-twelve hours.

With the above described embodiment of the timepiece the source ofenergy is located outside of the timepiece and is in the illustratedexample the battery of an automobile. However, the timepiece of theinvention, which may be a wrist watch instead of an automobile clock,may carry its own source of energy within its own house ing. Thus, Fig.4 shows an arrangement where the base plate 1 is provided with adepression which receives a miniature battery 32 which may have aterminal voltage of 1.3 volts, and this battery 32 is maintained withinthe depression 32a of the base plate 1 by an electrically conductivespringy member 30 which is affixed by a screw 31 to a block 29 ofinsulating material, this block being fixed in a known way as by a screwor the like to the base plate 1. The force of the spring 30 keeps thebattery 32 in position within the recess 31. The casing of the battery32 which engages the electrically conductive base plate 1 forms thenegative pole of the battery while the positive pole thereof is formedby the cover of the battery which engages the member 30. This member 30is insulated from the base plate 1 by the block 29, although if desiredthe member 30 can also be insulated from block 29 and screw 31 in anysuitable way as by suitable washers and a suitable sleeve into which thescrew 31 extends. With the arrangement of Fig. 4 the electricallyconductive springy member 30 is connected with a suitable lead to thepositive terminal 16 carried s by the support 13 while the negativeterminal 15 is in this case connected electrically with the base plate1.

Fig. 7 is a wiring diagram illustrating the electrical circuit ofthemeans for oscillating the tines of the vibrator. These means includea transistor which is preferably a germanium junction-type transistor,the base, emitter and collector electrodes of which are indicated at B,E, and C respectively. The positive terminal 16 of the voltage source(not shown) is electrically connected to the emitter E while thecollector C is connected to one terminal of the coil 12 which isapproximately five to six times the number of turns of the coil 11, aswas pointed out above. The other terminal of the coil,12 is connected tothe negative terminal 15 of the voltage source. A capacitor 40 isconnected in parallel with the coil 12, the capacitance of the capacitor40 and the inductance of the coil 12 being so selected that thecapacitor 40 and the coil 12 together form a tuned circuit which has aresonant frequency that corresponds substantially to the naturalfrequency of oscillation of the vibrator. In this way, the capacitor 40serves to prevent undesired oscillations. Also, the capacitor 34 andresistor 35 are connected in parallel with each other and this parallelcircuit is serially connected to one terminal of the coil 11 and to thenegative terminal 15 of the voltage source. The circuit is completed byconnecting the other terminal of the coil 11 to the base B of thetransistor.

' The above circuit, the operation of which will be more detailedlydescribed below, is a self-regulating one in that it will cause thetines to vibrate not only at their natural frequency, but also at asubstantially constant amplitude. In practice, the amplitude ofoscillation of the tines will be maintained between certainpredetermined minimum and maximum amplitudes. The significance anddesirability of this will become evident upon further consideration ofthe specification.

It will be seen from the above that the reciprocation of the pawl isbrought about by the oscillation or vibration of the vibrator 2, thelength of the stroke of reciprocation of the pawl being a function of ordependent upon the amplitude of oscillation of the tine 4. It will alsobe understood that the arrangement of the parts is such that normallyeach reciprocation of the pawl brings about an angular rotation of theratchet wheel which corresponds to the pitch of each ratchet tooth.Thus, the stroke length of the pawl must not only be sufiiciently greatso that the pawl will, during successive reciprocation, engage differentteeth, but also, the stroke length of the pawl should not be so greatthat the pawl engages, during successive reciprocations, non-successiveteeth. If the latter were to occur, i.e., if, during successivereciprocations, the pawl were occasionally to engage alternate teeth,that particular reciprocation of the pawl would be accompanied by adouble angular displacement of the ratchet wheel. Since, in practice, atimepiece particularly .of the watch type is often subjected to shocks,the amplitude of oscillation of the tuning fork may become sufficientlygreat, at least temporarily, so as to cause the pawl toengage, duringsuccessive reciprocations, nonadjacent or non-successive ratchet teeth.This, in turn, would bring about inconstant and inaccurate activation ofthe timepiece mechanism.

As may best be seen in Fig. 8, the pawl should move in such a mannerthat the tooth 20a, in a direction T tangential to the ratchet wheel atthe point of engagement between the tooth 20a and the ratchet wheel,reciprocates with a stroke the length of which is greater than thedistance P and smaller than twice this distance, the distance Prepresenting the pitch of the ratchet teeth. It is clear that if thetooth 20a does not reciprocate with a stroke the length of which exceedsthe distance P, the tooth 20a would not, during successivereciprocations, engage successive teeth but would instead simply remainin engagement with the same tooth. Also, it will be seen that if thetooth 20a reciprocates with a stroke the length 8 of which exceeds thedistance 2P, the tooth 20a would engage non-consecutive or alternateteeth. If this were to occur then each reciprocationduring which thestroke length of the tooth 20a exceeded the distance 2P would bringabout a double angular displacement of the ratchet wheel 21.

It will be readily understood that the stroke length of the tooth 20a inthe direction T is a function of or is dependent upon the amplitude ofoscillation of the tine 4. Thus, in order for the tooth 20a toreciprocate in the direction T with a stroke length equal to at least P,and, in practice, with a stroke length a which is somewhat greater thanP, the tine 4 will have to oscillate with a certain minimum amplitude.The above described electrical means shown schematically in Fig. 7 arecapable of oscillating the tine 4 at at least such minimum amplitude.

Also, it will be understood that in order for the stroke length of thetooth 20a not to exceed 2P, and, in practhe, not to exceed a length 0which is somewhat smaller than 2P, the amplitude of oscillation of thetine 4 may not exceed a certain maximum. The above described electricalmeans are so constructed as to oscillate the tines at an amplitude whichdoes not exceed a certain operating or normal maximum, which correspondsto reciprocation of the tooth 20a with a stroke length shown at b. As isclearly shown in Fig. 8, the stroke length I; is not only smaller than2P but is also somewhat smaller than the stroke length 0. However,shocks or other extraneous forces to which a timepiece is very oftenexposed may be sufficient to cause the tine 4 to oscillate at anexcessive amplitude, i.e., at an amplitude which exceeds that normalmaximum and which causes the tooth 20a to reciprocate with a strokelength greater than b. Such excessive oscillation may, prior to beingdamped to below the normal maximum amplitude, persist throughout aconsiderable number of cycles during each of which the ratchet wheel isadvanced an angular distance exceeding that corresponding to the pitchP.

The abutment 7b is therefore provided, and serves to prevent the tines 3and 4 from oscillating above an amplitude corresponding to the distances, as set forth above. Accordingly, the distance s is so selected thatthe tines 3 and 4 may oscillate at an absolute maximum amplitude whichcorresponds to reciprocation of the tooth 20a, in the direction T, witha stroke length less than 2?, for example with the stroke length shownat c. In this way, the tooth 20a cannot, during oscillation of thetuning fork, skip any of the teeth 21a of the ratchet wheel 21,irrespective of whether the tooth 20a is reciprocated by the tine 4during normal oscillation thereof under the influence of theabove-described electrical means or whether the tooth 20a isreciprocated by the tine 4 during excessive oscillation thereof underthe influence of extraneous vibrations. Consequently, each oscillationof the tuning fork and consequently each reciprocation of the pawl 20brings about an angular movement of the ratchet wheel 21 whichcorresponds to the pitch P of the ratchet teeth 21a, as disclosed incopending application Serial No. 570,958.

In practice, the electrical means for oscillating the tuning fork are soconstructed and arranged that the tines are oscillated at such amplitudeas will bring about reciprocation of the tooth 20a in the direction Twith a stroke length equal to approximately 1.5P. Thus, in Fig. 8 theforwardmost position of the tooth 20a is shown in solid lines whereasthe normal backwardmost position is shown in dotted lines.

it will be understood, therefore, that the electrical means normallyoscillate the tines at the amplitude, or within the amplitude range,necessary to cause reciprocation of the tooth 20a with the proper strokelength. The abutment element 7b is thus called upon to limit theamplitude of oscillation of the tines to the above described absolutemaximum only when the timepiece is exposed to shocks or other extraneousforces of such mag- 9 nitude as to cause the tines to oscillate at anamplitude greater than the normal maximum amplitude.

In the embodiment illustrated in Fig. 9, the tuning fork 102 havingtines 103 and 104 is adapted to be mounted on the base plate of thetimepiece mechanism by means of the member 105, the latter being screwedonto the base plate by means of screws 105a. The tines 103 and 104respectively carry a permanent magnet 106 and a balance weight 107, therespective centers of gravity of these members being in registrationwith the respective tines. The time 104 carries a pawl 120 having atooth 120a, as described above. The instant embodiment differs from theabove described one in that the abutment element 1071; instead of beingcarried by the balance weight 107 is carried by the permanent magnet106. As described above, the element 107!) may be made of nonmagneticmaterial, such as brass. If desired, however, the element 107!) may bemade of magnetic material but be magnetically insulated from thepermanent magnet 106 by means of a partition element 107b which is madeof nonmagnetic material. The right free end of the element 107b, asviewed in Fig. 9, is spaced a distance s from the balance weight 107,and the function and mode of operation of the device is identical tothat of the above described embodiment.

In the embodiment illustrated in Fig. 10, the tuning fork 202 havingtines 203 and 204 is adapted to be secured to the base plate of atimepiece by means of a member 205, the latter being screwed onto thebase plate by means of screws 205a. The tine 204 carries a pawl 220having a tooth 220a adapted to cooperate with the ratchet wheel in themanner described above. The tines 203 and 204 each carry a permanentmagnet 206, the respective centers of gravity of which are in alignmentor registration with the respective tines, so that the instantembodiment differs from the above described one in that two permanentmagnets are provided, there being no balance weight corresponding to theelement 7 of Fig. 1. In the instant embodiment of the electrical meansfor oscillating the tuning fork may be of the constructions described inthe above mentioned copending application Serial No. 436,949. One of thepermanent magnets 206 carries an abutment element 207k which is spacedfrom the other permanent magnet a distance s, the function and operationof the device being identical to the above described ones.

In the embodiment illustrated in Fig. ll, the tuning fork 302 includes apair of tines 303 and 304, the axis of symmetry of the tuning fork beingindicated by the line X-X. As in the above described embodiments, amember 305 serves to mount the tuning fork onto the base plate of atimepiece, as, for example, by means of screws 305a.

The tines of the tuning fork are inclined toward each other and convergetoward each other as they approach their free ends so that the tuningfork 302 has the substantially triangular configuration indicated inFig. 11. A pair of permanent magnetic drums 306 are fixed at their endfaces respectively to the outer faces of the free ends of the tines, itbeing understood that one of the drums 306 may be replaced by a suitablebalance weight of the type described in connection with the embodimentsillustrated in Figs. 1 and 9. The arrangement of the parts is such thatthe center of gravity of each gnet is spaced a distance D from the axisof symmetry XX. This distance is so selected as to be substantiallyequal to the distance D which is the distance that each point T isspaced from the axis of symmetry XX. The point T of each tine representsthat axis about which the center of gravity of each magnetic drum orbalance weight oscillates or pivots. In practice, the axis T of eachtine will be located in the lowermost third of the tine.

As a result, the frequency of oscillation of the tuning fork ismaintained constant at a desired value and only a minimum amount ofenergy is required to maintain the it? vibrations or oscillations, as isset forth in full in co pending. application Serial No. 565,451.

The tine 304 carries a pawl 320 having a tooth 320 2 which is adapted tocooperate with a ratchet wheel, in the manner described above, and oneof the tines carries the abutment element 30712 which is fixed to theinner face of the free end portion of the tine. As is clearly shown inFig. 11, the free end of the abutment element 30712v is spaced adistance s from the inner face of the free end portion of the other tineso as to limit the maxiamplitude of oscillation of the tuning fork.

In the embodiment illustrated in Fig. 12, each of the tines 403 and 404carries a permanent magnet 406, it being understood that one of thepermanent magnets may be replaced by a suitable balance weight. Theinstant embodiment differs from the above described ones in that each ofthe permanent magnets 406 carries an abutment element 407b, theseelements being spaced from each other a distance s and cooperating witheach other in such a manner that when the amplitude of oscillation ofthe tines is equal to the maximum permissible amplitude, the abutmentelements will engage each other thereby preventing the tines fromoscillating at an amplitude greater than this maximum amplitude.

In the embodiment illustrated in Fig. 13, the tines 503 and 504 eachcarry a permanent magnet 506, it being understood that one of thepermanent magnets may be replaced by a suitable balance weight. In theinstant embodiment, each of the permanent magnets 506 either carries oris formed with an abutment portion 507!) which may be substantiallyfrusto-conical or domeshaped as shown in Fig. 13. The respectiveinwardmost parts of the portion 507!) are spaced from each other adistance s, thereby limiting the maximum amplitude of oscillation of thetines.

Additionally, it will be understood that any suitably shaped abutmentmeans may be provided for limiting the maximum amplitude of oscillationof the tines. For example, the abutment means may be connected to or beintegral with the tines proper. Also, it is not essential that theabutment means be located between the free end portions of the tines,and they may be so arranged as to be located physically exteriorly ofthe space between the tines.

Figs. 14 to 19 illustrate. on an enlarged scale, different embodimentsof motion transformer mechanisms a apted to be incorporated in atimepiece of the character described. In each of the followingembodiments the structural deta ls of the timepiece, including thetuning-fork type vib ator, the electrical means for oscillating thetines, and the abutment means for limiting the maximum amplitude ofoscillation of the tines may be identical to any of the above-describedarrangements. The motion transformer mechanisms shown in Figs. 14- 19,wh ch are disclosed in copending applications. Serial Io. 547,510 andSerial No. 580,813, filed April 26, 1956, ind entitled MotionTransformer, ditter from the motion transformer described above in thatdriving means are provided which are connected to the vibrator formovement therewith and which frictionally engage rotary means that serveto drive the timepiece at a rate directly proportional to the speed ofrotation of such rotary means. Additionally, suitable means are providedfor limiting the rotary means to continuous rotation in one direction.

In the embodiment illustrated in Fig, 14, the tuning fork has a pair oftines 603 and 604 carrying a magnetic drum 606 and a balance weight 607,respectively, the latter carrying an abutment element 607!) the free endof which is spaced at distance s from the drum 606 when the tines are atrest. The tine 604 also carries a driving means composed of a leafspring 620 firmly secured at one end to the tine 604 and a frictionelement 620a carried by the leaf spring 620 at its free end. Thetriotion element 620a may be made of a suitable synthetic material or ofa precious or semi-precious stone, as, for

example, ruby or sapphire, and is adapted to engage the crests of theteeth of the ratchet wheel 621 which is rotatably mounted at 621a andserves to drive the timepiece mechanism of the timepiece. The crestsconstitute a discontinuous outer peripheral friction surface so thatwhen the driving means is reciprocated in a direction T tangential tothe ratchet wheel at the point of engagement between the frictionelement 620a and the ratchet wheel, the ratchet wheel is oscillatedabout its turning axis 621a. Thus, the ratchet wheel is rotated in acounter-clockwise direction, shown by arrow 640, when the driving meansmoves leftwardly, as viewed in Fig. 14, whereas the ratchet wheel isrotated in a clockwise direction, shown by arrow 640a, when the drivingmeans moves rightwardly.

A pawl means is provided for limiting the ratchet wheel 621 tocontinuous rotation in the direction of the arrow 640. The pawl meansincludes a leaf spring 630 firmly secured at one end to the timepiecebase plate 601 and a pawl element 630a carried by the leaf spring 630 atits free end.

With the pitch of the ratchet teeth being indicated at '1, it will beunderstood that the pawl means prevents rotation of the ratchet wheel621, in the direction of the arrow 640a, an angular distance exceedingan angular distance corresponding to the pitch P, so that continuousrotation of the ratchet wheel is limited to rotation in the direction ofthe arrow 640. It will also be understood that in order for eachoscillation of the tine 604 to be accompanied bv angular displacement ofthe ratchet wheel a distance corresponding to the pitch P, the length ofthe stroke of reciprocation of the driving means should be not less thanP and not greater than 2P.

As set forth above, the stroke length of the driving means is a functionof or dependent upon the amplitude of oscillation of the tines of thevibrator, so that the tines will have to oscillate with a certainminimum amplitude to cause the driving means to reciprocate with astroke length at least equal to P. The above described electrical meansshown in Fig. 7 are capable of oscillating the tine 604 at at least suchminimum amplitude. Furthermore, the distance s is so selected that theabsolute maximum amplitude of oscillation of the tines is one at whichthe stroke length of the driving means does not exceed 2P. As set forthabove, the electrical means will oscillate the tines at an amplitude notexceeding a normal maximum amplitude which is not only smaller than 2Pbut which is also smaller than the absolute maximum at which the tinesmay oscillate. Thus, the abutment element 6071; serves mainly to preventexcessive oscillation of the tines in the event the timepiece is exposedto relatively severe shocks or other extraneous forces.

In practice, the electrical means are so constructed as to oscillate thetines with such an amplitude that the driving means reciprocates with astroke length equal to approximately 1.5P. It will be understood fromthe above that the pawl means will, during successive reciprocations ofthe driving means, be engaged by successive ratchet teeth.

In this way, each oscillation of the tines first displaces the ratchetwheel 621, in the direction of the arrow 640, an angular distancecorresponding to approximately 1.5P and thereafter, in the direction ofthe arrow 640a, an angular distance corresponding to approximately 0.5P.The net or effective displacement of the ratchet wheel during eachoscillation of the tines is therefore an angular distance correspondingto exactly 1.0P in the direction of the arrow 640, so that the timepiecemechanism is driven at a rate directly proportional to the frequency ofoscillation of the vibrator. Since the same has an extremely high degreeof constancy, the timepiece mechanism is driven very accurately.

In order to insure proper operation, the natural frequency of thedriving means is considerably greater than that of the vibrator. Inpractice, the natural frequency of the leaf spring 620 and the frictionelement 62044 should be at least twice as great as that of the tines ofthe vibrator.

In the embodiment illustrated in Fig. 15, the tuning fork has a pair oftines 703 and 704 carrying a magnetic drum 706 and a balance weight 707,respectively. The balance weight carries an abutment element 707k thefree end of which is spaced a distance s from the drum 706 when thetines are at rest. The tine 704 further carries a driv ing meansconstituted by a leaf spring 720 firmly secured at one end to the time704. The free end of the leaf spring 720 is adapted frictionally toengage the outer peripheral friction surface 721b of a friction wheel721b which, together with the ratchet wheel 721, forms a rotary meansfor driving the timepiece mechanism, the rotary means being turnablymounted on the base plate of the timepiece at 721a. A pawl means isprovided for limiting the rotary means to continuous rotation in thedirection of the arrow 740. The pawl means includes a leaf spring 730firmly secured at one end to the base plate 701 and a pawl element 730acarried by the leaf spring 730 at its free end.

The operation of the device is identical to that of the embodimentillustrated in Fig. 14. It will be understood, however, that theselection of the distance s will be influenced by the ratio r /r with rbeing the radius of the friction wheel 721b and r being the radius ofthe ratchet wheel 721.

In the motion transformer illustrated in Figs. 16 and 17, the tuningfork has a pair of tines 803 and 804 carry ing a magnetic drum 806and abalance weight 807, respectively. The balance weight carries an abutmentelement 80717 the free end of which is spaced a distance s from the drum806 when the tines are at rest. The tine 804 is connected to a drivingmeans for converting the oscillations of the vibrator to rotation of theratchet wheel 821 which is rotatably mounted on the timepiece base plate801 at 821a. The driving means includes a wire one end of which is fixedto the tine 804 and the other end of which is fixed to a coil spring820a, the latter being secured to the base plate. Preferably, themounting of the coil spring 820:: is such that one of its ends isintroduced into a bore within which it is retained by a tapered pin orwedge 801a. In this way, not only is the wire resiliently coupled to thevibrator, but also, the tension of the spring 820a and consequently thetension of the wire 820 may be adjusted.

It will be seen that the wire 820 thus reciprocates during oscillationof the tines of the vibrator, the coil spring 820a being tensionedduring leftward movement of the tine 804 and serving to draw the wire820 during rightward movement of this tine.

The wire 820 seats within the longitudinal groove 850a of a frictionelement 850, the underside of which bears with a slight pressure on thediscontinuous outer peripheral friction surface of the ratchet wheelformed by the crests of the ratchet teeth. The friction element 850 ispreferably of a very light material and may have its underside linedwith a suitable plastic material 8501; in order to improve the frictionbetween the underside of the friction element and the ratchet teeth andalso so as to prevent excessive Wear of the underside. i

The friction between the friction element 850 and the wire 820 issufliciently great so that the friction element moves with the wire andthus reciprocates during oscil lation of the vibrator. As a result, whenthe tine 804 and consequently the friction element 850 move leftwardlyin a direction T tangential to the ratchet wheel at the at the point ofcontact between the ratchet wheel and the friction element, the ratchetwheel 823. is turned in a counter-clockwise direction, shown by arrow840, and when the friction element 850 moves rightwardly, the ratchetwheel is turned in a clockwise direction, shown by arrow 840a.

Suitable pawl means are provided for preventing continuous rotation ofthe ratchet wheel 821 in the direction of the arrow 840a, and mayinclude a very thin resilient w en leaf 806 preferably made of aplastic, one end of which leaf bears with a slight pressure on one ofthe ratchet teeth. As a result, when rotation of the ratchet wheel 821in the direction of the arrow 840a is prevented during rightwardmovement of the friction element 050, the same slides over thediscontinuous outer peripheral friction surface constituted by thecrests of the ratchet teeth.

For the reasons set forth above in connection with the embodimentsillustrated in Figs. 14 and 15, the length of the stroke ofreciprocation of the friction element 850 should be at least as great asP and not greater than 2P, with P being the pitch of the ratchet teethof the ratchet wheel 821. While the maximum amplitude of oscillation ofthe tines is determined by the distance r, it is possible, according tothe instant embodiment, to limit the stroke length of the frictionelement 350 directly, i.e., independently of the maximum possibleamplitude of osciilation of the tines.

This may be accomplished by providing abutments or stops 860 and 861adapted to be engaged by the opposite end-s of the friction element 350,respectively. The distance between the stops S60 and 861, in thedirection T, is greater than the length of the friction element 850 and,in any one position of the friction element, one of its ends is spaced adistance d from the stop 860 and the other of its ends is spaced adistance d from the stop 861. As a result, the maximum length of thestroke of reciprocation of the friction element 850 is equal to d-l-d'.This sum should, for the reasons set forth above, be less than 2?.

It will also be understood, for the reasons set forth above, that thelength of the stroke of reciprocation of the friction element 854)should not be less than P. Consequently, the sum d+d should besufficiently great to permit the friction element 850 to reciprocatewith a stroke length greater than P so that the following relationshould be satisfied: 2P d+d' P. Thus, when the tines are oscillated withan amplitude sufiicient to cause the wire 820 to reciprocate with astroke length greater than P, each oscillation of the tine 4 will beaccompanied by an angular displacement of the ratchet wheel 821 in thedirection of the arrow 840 an effective angular distance correspondingto the pitch of the ratchet teeth.

In practice, the tines are oscillated at such amplitude that the strokelength of the friction element 850 is approximately 1.5P, so that thestops 860 and 861 are engaged only when, as a result of shocks,excessive oscillations are imparted to the tine. In that event, thefriction element will, at each end of the stroke, engage one of thestops, the wire 820 being free to slide relative to the friction elementwhen movement thereof is prevented. In this way, shocks occurring whenthe friction element 850 engages the stops 860 and 861 are dampened.

In order to insure proper operation of the motion transformer, thenatural frequency of the moving parts, such above described one in thatthe friction element 950 is fixed to the wire 920. The latter isconnected at one end to the base plate by means of a coil spring 920aand at the other end to the tine 9134 by means of another coil spring9201). In this way, shocks occurring when the friction elements 950engages the stops are dampened.

As in the above described embodiment, the natural frequency of themoving parts, including that of the coil spring 920b, should be higherthan the frequency of oscillation of the vibrator.

In each of the two embodiments shown in Figs. 16 to 18, the wire is sodisposed that the friction element bears on the ratchet wheel withsufficient pressure to impart a rotary movement thereto. In some cases,it may be desirable to exert an additional pressure on the friction 14element in order to insure good frictional contact between the elementand the teeth of the ratchet wheel.

Such positive contact may be attained in either of the arrangementsshown in Figs. 16 to 18 by means of the construction shown in Fig. 19.An arched leaf spring 1060 is fixed at one end to the timepiece baseplate by means of a pin or screw 1061, the other end of the springbearing on the upper side of the friction element 1050. The spring 1060is convex toward the tine 1004 so that when the friction element 1050moves leftwardly, i.e., in a direction which brings about rotation ofthe ratchet wheel 1021 in the direction of the arrow 1040, the spring1060 is compressed and exerts a greater force on the friction element1050, whereas when the friction element moves rightwardly, i.e., in adirection which tends to bring about rotation of the ratchet wheel inthe direction of the arrow 1040a, the pressure exerted by the spring1060 tends to reduce.

While the motion transformers illustrated in Figs. 14 to 19 have beendescribed as inconporating a tuning fork, a magnetic drum, a balanceweight and an abutment element of the type shown in Fig. 1, it will beunderstood that any one of these motion transformers may incorporate anysuitably shaped vibrator, as, for example, any one of the types shown inFigs. 9' to 11. Similarly, any one of motion transformers shown in Figs.14 to 19 may be used in conjunction with a tuning-fork type vibratoreach tine of which carries a magnetic drum rather than a tuning-forktype vibrator wherein one tine carries a magnetic drum and the othertine carries a balance weight. Also, the abutment means carried by thetines may include one or two abutment elements, or be otherwise suitablyshaped, as, for example, in the manner described above and illustratedin Figs. 9 to 13.

Fig. 20 is a fragmentary perspective view, partly in section and on anenlarged scale, of a tuning-fork type vibrator 1102, and electricalmeans for oscillating the same. The instant embodiment differs from thatshown in Fig. 1 in that each of the tines 1103 and 1104 carries anelectric component which is part of the electrical means, there being nobalance weight corresponding to the element 7 of Fig. 1.

The vibrator is operatively associated with a driving means which formspart of a motion transformer for converting oscillations of the vibratorto rotary movement of the hands of the timepiece. In the instantembodiment, the motion transformer is of the pawl and ratchet typeshown, for example, in Fig. 1, but it will be understood that thevibrator may be used in conjunction with any suitable type of motiontransformer, including any one of the types shown in the precedingfigures.

The pawl and ratchet mechanism shown in Fig. 20 includes a pawl 1120carried by the tine 1104, a tooth 1120a being provided at the free endof the pawl. The tooth cooperates with the ratchet teeth 1121a of arotatably mounted ratchet wheel 1121 in such a manner that the ratchetwheel is caused to rotate in the direction of the arrow 1140 duringoscillation of the tine 1104. A friction wheel 1121b which is mountedfor rotation to- .gether with the ratchet wheel 1121 is engaged by aleaf spring 11210 which is carried by the base 1101 of the timepiece.The friction wheel 1121b and leaf spring 1121c constitute a brake forpreventing rotation of the ratchet wheel under the influence of anythingother than the pawl 1120. The braking action also acts to preventbackward rotation of the ratchet wheel when the pawl is retracted.

The ratchet teeth 1121a have a pitch P, so that stroke of reciprocationof the tooth 1120a, in a direction tangential to the ratchet wheel atthe point of engagement of the tooth and the ratchet wheel, should benot less than P and not greater than 2P, for the reasons set forth infull above.

The electrical means for oscillating the tines compriseelectromechanical driving means capable of converting 15 electricalenergy into mechanical energy for oscillating the vibrator,electromechanical sensing means capable of converting mechanical energyinto electrical energy and responsive to the oscillation of the vibratorfor producing an electrical signal which is a function of the amplitudethereof, and electrical energy supplying means connected in circuit withthe driving means and the sensing means for supplying electrical energyto the former in a manner dependent upon or controlled by the electricalsignal produced by the latter. Each of these electromechanical meansincludes a magnetic field producing component and a magnetic fieldresponsive component which is in circuit with the electrical energysupplying means, one of which component is carried by the vibrator formovement therewith during oscillation thereof and the other of whichcomponents is carried by the base of the timepiece and cooperates withthe one component in such a manner that oscillation of the vibrator isconcomitant with the existence of a voltage across the magnetic fieldresponsive component.

In the embodiment illustrated in Fig. 20, the magnetic field producingcomponents of the electro-mechanical means are carried by the tines 1103and 1104, respectively. Each of these magnetic field producingcomponents is constituted by a substantially cup-shaped permanent magnet1106 which is formed with a rim portion and a central boss portion, theformer being shown as constituting an S pole and the latter asconstituting a N pole. These portions define an annular space betweenthemselves, as is clearly shown in the drawing. If desired, the centralboss portion may be omitted and the magnetic characteristics may beimparted to the components 1106 by providing a permanent bar magnet inplace of this boss portion so that the components 1106 resemble themagnet field producing means 6, 6a of Fig. 1.

One of the magnets 1106 carries an abutment element 1107b the free endof which is spaced a distance s from the other magnet 1106, thusestablishing the absolute maximum amplitude at which the tines 1103 and1104 can oscillate.

Each of the magnets 1106 cooperates with a magnet field responsivecomponent which, in the embodiment shown in Fig. 20, is constituted by acoil. The coil associated with one of the magnets 1106 is a sensing coilindicated as Sc and the coil associated with the other magnet 1106 is adriving coil indicated as D which has approximately five to six times asmany turns as the sensing coil Sc. Each coil is carried by a stationarytubular carrier 1110 which is fixed to a support 1113, each support inturn being mounted to the base plate of the timep1ece (not shown in Fig.20). The arrangement of the parts is such that the coils extend into theannular spaces formed by the rim and boss portions of the respectivemagnets 1106, there being sufiicient clearance between the outer surfaceof each coil and the inner surface of the rim portion of thecorresponding magnet as well as between the inner surface of eachtubular carrier 1110 and the outer surface of the boss portion of thecorresponding magnet to permit reciprocation of the magnets relative tothe coils during oscillation of the tines. ,It will be understood,therefore, that oscillation of the tines is concomitant with theexistence of a voltage across the coils, the amplitude of oscillationand the amplitude of the voltage being interdependent upon each other.Thus, each coil together with its cooperating magnet forms anelectro-mechanical transducer.

More particularly, the driving coil D together with its cooperatingmagnet 1106 forms an electro-rnechanical driving means capable ofconverting electrical energy into mechanical energy, i.e., a voltageplaced across the driving coil D will cause movement of the cooperatingmagnet and an alternating voltage will cause reciprocation of the magnetand consequently oscillation of time 1104 and; by force, of tine 1103since it is one of the basic characteristics of a tuning-fork typevibrator that its tines oscillate together. The amplitude of oscillationof the tines will depend upon the amplitude of the voltage placed acrossthe driving coil.

Similarly, the sensing coil Sc together with its cooperating magnet 1106forms an electro-mechanical sensing means capable of convertingmechanical energy into electrical energy, i.e., oscillation of the tine1104 and reciprocation of the associated magnet 1106 will induce analternating voltage across the sensing coil Sc, the amplitude of thisinduced voltage being dependent upon the amplitude of oscillation of thetine 1104.

The coils S and D are connected in circuit with the electrical energysupplying means. The latter is responsive to the signal or controlvoltage induced in the sensing coil and produces a driving voltageacross the driving coil which is a function of the amplitude of thesignal, the arrangement being such that the control voltage which, byvirtue of the fact that the sensing coil has fewer turns than thedriving coil, is smaller than the driving voltage, is amplified in sucha manner as to maintain the driving voltage constant.

In the arrangement shown in Figs. 20 and 21, the electrical energysupplying means includes a transistor TR having base, emitter andcollector electrodes respectively indicated at B, E and C, a battery orother suitable source of voltage B, a capacitor C and a resistor R. Thetransistor is preferably a germanium junction transistor and the batteryis preferably one the terminal voltage of which, throughoutsubstantially the entire useful life of the battery, remainssubstantially constant, with the voltage decreasing sharply only whenthe battery is almost completely discharged. For example, the batterymay be of the mercury-cell type having a terminal voltage ofapproximately 1.3 v.

The capacitor C having a capacitance of the orderof 2 microfarads andthe resistor R having a resistance of the order of 2 megohms areconnected in parallel with each other, and the parallel circuit is inseries with the sensing coil Sc so as to form a series circuit oneterminal of which is connected to the transistor base and the other ofwhich is connected -to the positive terminal of the battery. Thenegative terminal of the battery is connected to one terminal of thedriving coil D and forms another series circuit therewith, the terminalsof which are constituted by the opposite terminal of the coil D and by.the positive terminal of the battery, respectively. This last-mentionedterminal of the coil D is connected to the transistor collector, and thetransistor emitter is connected to the positive terminal of the batteryso as to complete the circuit, as shown in Figs. 20 and 21. Thus, theinstant circuit difiers from that illustrated in Fig. 7 in that thebattery B is in the collector branch instead of the emitter branch, itbeing clear, however, that the mode of operation of either arrangementis almost the same. Circuit on Fig. 7 gives a better starting of theoscillation and a smaller variation of 1 caused by amplitude variation.Also, the additional capacitor in parallel with the driving coil D isnot necessary when D and Sc coils are on separated magnets or if theelectrical coupling between coils D and Sc is so small that no wildoscillation will come up.

Alternatively, the battery may be interposed between .the driving coil Dand the collector, in which event one terminal of the driving coil D isconnected to the positive terminal of the battery, the negative terminalthereof being connected to the collector. The emitter and the oneterminal of the sensing coilcapacitor series circuit are connected tothe free terminal of the driving coil.

The operation of the electrical means including the sensing means, thedriving means and the electrical energy supplying means is as follows:

The instantaneous amplitude of oscillation of the tines may berepresented 17 where A is the peak amplitude of the tine measured as thecenter of gravity of the respective permanent magnet 1106, and the rateof travel .or velocity of the magnet may then be expressed by With n dand B representing the number of turns and the diameter of the sensingcoil Sc and the flux density of the magnet 1106 associated therewith,and with n d and E representing the number of turns and the diameter ofthe driving coil D and the flux density of the magnet 1106 associatedtherewith, the voltages across these coils may be represented asfollows:

so that it will be seen that oscillation of the tines is concomitantwith the existence of a voltage across each of the coils, which voltagesare proportional to the peak amplitude of oscillation of the tines.

With the coil Sc being considered the driven or sensing coil, the .abovementioned voltage V is induced thereacross during oscillation of thetines, and the base voltage V may then be expressed as follows:

with V being the voltage across the capacitor C, the latter constitutinga DC voltage source which is capable of temporarily retaining a voltagegenerated by the coil S and the diode base-emitter of the transistor andof supplying this voltage as a negative bias for biasing the transistorin such a manner that the same is in class C operation. If desired, thecapacitor C may be replaced by a battery or other voltage source forsupplying the desired biasing voltage, but the oscillator will not startitself.

The alternating voltage V causes the base current I to vary in themanner shown in Fig. 22, and the changing base current, in turn,controls the collector current I in such a manner that its configurationor wave shape may assume that shown in the same figure.

At the same time, the battery B will cause a collector current I to flowthrough the driving coil D so that the same produces the driving voltageV which is equal to with V representing the battery voltage and V thecollector voltage. The latter may be expressed as follows:

with V being the collector voltage at the instant I is greatest. Theconstruction of the whole circuit is such that so that, inasmuch as thetransistor has characteristics analogous to that of a pentode in thatthe collector current I is very strongly influenced when changes in thecollector voltage V occur within the range of 0 to 0.3 v., small changesin the collector voltage brought about by small changes in the voltage Vacross the driving coil D produce relatively large changes in thecollector current I and that alone stabilizes the amplitude.

The entire electrical means are thus capable not only of driving thetines, but serve as an automatic regulator for oscillating the tines ata constant amplitude, the significance of which is described above. Thevariation of V has no stabilizing effect, this voltage only determinesthe moment, when the current I has to flow which current causes a Icurrent. But the volume of I is determined by the voltage V min. Theamplitude stabilizing effect is limited at a current I max. This I: max.

will come up when for instance under the influence of increased frictionin the timepiece mechanism the voltage V min. will be greater than 0 3volts which is about the knee of the pentode characteristic of ajunction transistor. Then for V min. greater than 0 3 volts the currentI max. is current amplification factor of the transistor multiplied by 1max. With capacitor-resistor biasing and these two connected on thenegative pole of the battery as shown in Fig. 21 the current I, max. isalmost independent on variations of V caused by variations of theamplitude. This I, max. must be chosen by calculating the resistor whichis parallel to the capacitor in such a manner that the greatest frictionwhich may occur in the timepiece produces a current I which is stillsmaller than 1 min. as described above. Now the amplitude stabilizingeffect, which works only in the region of O to 0 3 volts for V min. isregulating like this:

There may be a decrease in amplitude of oscillation caused by frictionin the timepiece. The voltage V will therefore decrease what makesincrease the voltage V min. and this causes a very big increasing of thecurrent 1 which current drives the tuning fork again to greateramplitude of oscillation, or with other words a very small variation inamplitude of oscillation in the described regulating area causes verybig driving energy variations conducted to the tuning fork.

It will be seen, therefore, that the amplitude of oscillation of thetines is automatically maintained between certain minimum and maximumamplitudes so that the pawl means 1120, 112th: are reciprocated with astroke the length of which is maintained between certain minimum andmaximum lengths. These minimum and maximum amplitudes are the extremeamplitudes of a very narrow range of amplitudes, so that for practicalpurposes the amplitude of oscillation of the tines is maintainedconstant at that amplitude at which the base and collector voltages andcurrents assume the values shown in Fig. 22. For the reasons set forthabove, this amplitude corresponds to a reciprocation of the pawl meanswith a stroke the length of which is equal to approximately 1.5P.

As also set forth above, a separate battery may be substituted for thecapacitor C. However, not only has it been found to be more practical toprovide a capacitortype bias source instead of a battery, but also, thecapacitor serves to bring about a relatively small change in the basecurrent during relatively large changes in the voltage V due to theautomatic bias action.

Also, the capacitor resistor-type bias voltage source serves to drivethe base voltage positive during at least a portion of the cycle,despite the occurrence of a relatively sharp amplitude decrease. With abattery biasing in this case the oscillation would stop because I wouldbe 0. This condition is prevented by providing the biasing capacitor Cand resistor R which at all times supplies a negative biasing of suchmagnitude as to drive the base current positive during a portion of thecycle. In this way, the tines will be returned to normal amplitudeoscillation even after a sharp amplitude decrease.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofelectric timepieces differing from the types described above.

While the invention has been illustrated and described as embodied in anelectric timepiece incorporating a tuning-fork type vibrator, it is notintended to be limited to the details shown, since various modificationsand structural changes may be made without departing in any way from thespirit of the present invention.

For example, the physical arrangement of the sensing and driving coilsmay differ from that shown in Fig. 1 wherein both coils are associatedwith a single magnet carried by one tine or in Fig. 20 wherein the coilsare associated with different magnets carried by different tines. Ifdesired, either the driving coil or the sensing coil or both mayconstituted by two separate coils which are serially connected to eachother, with one of these separate coils being associated with the magnetcarried by one of the tines and with the other being associated with themagnet carried by the other tine. Thus, the total space available forthe sensing and driving coilswhich, in a timepiece of the characterdescribed, may be extremely small-may be utilized to best advantage,i.e., the total physical space requirement of both the sensing anddriving coils may be evenly divided between the two magnets.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a timepiece having a timepiece mechanism, in combination, a base;ratchet wheel means having ratchet teeth of predetermined pitch andbeing rotatably carried by said base, said ratchet wheel means beingoperatively associated with said timepiece mechanism for driving thesame at a rate directly proportional to the speed of rotation of saidratchet wheel means; reciprocatable driving means cooperating with saidratchet wheel means for rotating the same when the length of the strokeof reciprocation of said driving means is between a predeterminedminimum stroke length which is a function of the pitch of said ratchetteeth and a predetermined absolute maximum stroke length which is afunction of twice the pitch of said ratchet teeth; a tuning-fork typevibrator carried by said base and having a pair of tines capable ofoscillating at a constant frequency, one of said tines being connectedto said driving means for reciprocating the same with a stroke thelength of which is a function of the amplitude of oscillation of saidtines, each oscillation of said one tine bringing about one ricprocationof said driving means; abutment means for limiting the amplitude ofoscillation of said tines to an absolute maximum amplitude ofoscillation at which the stroke length of said driving means equals saidpredetermined absolute maximum stroke length; and electrical means fornor mally oscillating said tines of said vibrator at said constantfrequency and at a constant amplitude at which the stroke length of saiddriving means is between said predetermined minimum stroke length and apredetermined normal maximum stroke length which is less than saidabsolute maximum length so that said driving means, while beingreciprocated by said one tine during normal oscillation thereof underthe influence of said electrical means as well as while beingreciprocated by said one tine during excessive oscillation thereof underthe influence of extraneous vibrations, may rotate said ratchet wheelmeans at a constant speed so that said ratchet wheel means in turn maydrive said timepiece mechanism at a constant rate, said constant speedof rotation of said ratchet wheel means and consequently the rate atwhich the same drives said timepiece mechanism being directlyproportional to said constant frequency, whereby said timepiecemechanism is driven at said constant rate despite excessive oscillationimpanted to said tines of said vibrator extraneously.

2. The combination defined in claim 1 wherein said abutment meansinclude at least one abutment element arranged between said tines,carried by one of said tines adapted to engage the other of said tines.

3. The combination defined in claim 1 wherein said abutment meansinclude a pair of abutment elements ar ranged between said tines andcarried by said tines, respectively, said abutment elements beingadapted to engage each other. 1

References Cited in the file of this patent FOREIGN PATENTS 767,359France May 1, 1934

